Coastal land subsidence accelerates timelines for future flood exposure in Hawai'i

Abstract Coastal subsidence exacerbates relative sea level rise, making low-lying areas vulnerable to flooding. In Hawai’i, the contribution of vertical land motion has not been fully studied. This is critical for urban O’ahu, where infrastructure is on low-lying coastal areas with varying sedimenta...

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Main Authors: Kyle Murray, Matthew Barbee, Philip Thompson, Charles Fletcher
Format: Article
Language:English
Published: Nature Portfolio 2025-02-01
Series:Communications Earth & Environment
Online Access:https://doi.org/10.1038/s43247-025-02108-4
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author Kyle Murray
Matthew Barbee
Philip Thompson
Charles Fletcher
author_facet Kyle Murray
Matthew Barbee
Philip Thompson
Charles Fletcher
author_sort Kyle Murray
collection DOAJ
description Abstract Coastal subsidence exacerbates relative sea level rise, making low-lying areas vulnerable to flooding. In Hawai’i, the contribution of vertical land motion has not been fully studied. This is critical for urban O’ahu, where infrastructure is on low-lying coastal areas with varying sedimentary consolidation. Here we processed Interferometric Synthetic Aperture Radar data from 2006–2024 for the Hawaiian Islands, referencing them with Global Navigation Satellite System measurements to calculate subsidence rates. We also created a two-meter resolution digital elevation model for coastal O’ahu using 2007–2013 Federal Light Detection and Ranging data, which included hydro-enforcement and gap filling with reprocessed data. Using this elevation data and vertical land motion measurements, we numerically modeled flood exposure. Results suggest that while island-wide subsidence on O’ahu is about 0.6 ± 0.6 m m/y r, the south shore has localized rates exceeding 25.0 ± 1.0 m m/y r. This subsidence, which is much faster than Hawaii’s long-term sea level rise rate (1.54 mm/yr since 1905), could expand flood exposure by up to 53% by 2050 in the Mapunapuna industrial region. Accounting for subsidence compresses the timeline for flood preparedness by up to 50 years, emphasizing the need to integrate these insights into planning and policy for sustainable development and flood mitigation.
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spelling doaj-art-9ab3dca469b5466ea4b39970dc4549442025-08-20T02:15:08ZengNature PortfolioCommunications Earth & Environment2662-44352025-02-016111010.1038/s43247-025-02108-4Coastal land subsidence accelerates timelines for future flood exposure in Hawai'iKyle Murray0Matthew Barbee1Philip Thompson2Charles Fletcher3University of Hawai’i Manoa, Earth SciencesUniversity of Hawai’i Manoa, Earth SciencesUniversity of Hawai’i Manoa, OceanographyUniversity of Hawai’i Manoa, Earth SciencesAbstract Coastal subsidence exacerbates relative sea level rise, making low-lying areas vulnerable to flooding. In Hawai’i, the contribution of vertical land motion has not been fully studied. This is critical for urban O’ahu, where infrastructure is on low-lying coastal areas with varying sedimentary consolidation. Here we processed Interferometric Synthetic Aperture Radar data from 2006–2024 for the Hawaiian Islands, referencing them with Global Navigation Satellite System measurements to calculate subsidence rates. We also created a two-meter resolution digital elevation model for coastal O’ahu using 2007–2013 Federal Light Detection and Ranging data, which included hydro-enforcement and gap filling with reprocessed data. Using this elevation data and vertical land motion measurements, we numerically modeled flood exposure. Results suggest that while island-wide subsidence on O’ahu is about 0.6 ± 0.6 m m/y r, the south shore has localized rates exceeding 25.0 ± 1.0 m m/y r. This subsidence, which is much faster than Hawaii’s long-term sea level rise rate (1.54 mm/yr since 1905), could expand flood exposure by up to 53% by 2050 in the Mapunapuna industrial region. Accounting for subsidence compresses the timeline for flood preparedness by up to 50 years, emphasizing the need to integrate these insights into planning and policy for sustainable development and flood mitigation.https://doi.org/10.1038/s43247-025-02108-4
spellingShingle Kyle Murray
Matthew Barbee
Philip Thompson
Charles Fletcher
Coastal land subsidence accelerates timelines for future flood exposure in Hawai'i
Communications Earth & Environment
title Coastal land subsidence accelerates timelines for future flood exposure in Hawai'i
title_full Coastal land subsidence accelerates timelines for future flood exposure in Hawai'i
title_fullStr Coastal land subsidence accelerates timelines for future flood exposure in Hawai'i
title_full_unstemmed Coastal land subsidence accelerates timelines for future flood exposure in Hawai'i
title_short Coastal land subsidence accelerates timelines for future flood exposure in Hawai'i
title_sort coastal land subsidence accelerates timelines for future flood exposure in hawai i
url https://doi.org/10.1038/s43247-025-02108-4
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